Cory Monteith In His Final Film Role: See the Photo

Cory Monteith's last film role was a big departure from the sweet and innocent character he played on Glee.

In a new photo from his final film, McCanick, the late star sports long hair to play a drug-addicted criminal sent to prison for murder.

The film is set to make its debut at the Toronto Film Festival in September, and its director tells PEOPLE that Monteith, who died of a lethal combination of heroin and alcohol on July 13, knew he could play the character because of his troubled past.

"He opened up quite a bit," Josh C. Waller tells PEOPLE of their meeting for the movie that was shot last September. "He was like, 'I can do this character. I know this character. I was this character. I have lived elements of this.' He said, 'I was a troubled youth.' "

It's exactly a month since Monteith was found dead in a Vancouver hotel room. His Glee castmates, including Monteith's girlfriend of one year, Lea Michele, are currently prepping to shoot a tribute episode for the actor, which will air in October.

Fans of Monteith may make donations in his name to three charities that were especially important to him: Project Limelight Society, which exposes youth living in Vancouver's Downtown Eastside to the arts; Virgin Unite, founded to support entrepreneurial efforts to better the world; and , which helps homeless and low-income individuals find employment.